There are many hypotheses about the relationship between therapod dinosaur and the
origin of birds. The most widely accepted hypothesis on the origin of birds is that birds
evolved from a group of therapods called maniraptorian. Within the last decade, the line
between what is a dinosaur and what is a bird has been blurred. An accumulation of new
discoveries has opened a Pandora’s box of debate over the origin of birds. The recent
discovery of Microraptor gui, presumably a feathered dinosaur, has added fuel to the fire
of what characters define a dinosaur or bird and the origin of birds. Microraptor gui was
discovered in the Jiufotang formation in western Liaoning, China. Microraptor gui is 77
cm in length with four wings. The feature that makes Microraptor gui unique is that its
the first dinosaur with a wing on each hind-limb. At first glance one would think that
Microraptor gui would be a bird. The evidence supporting Microraptor gui being a bird
is that feathers are present covering the whole body and its forelimbs to form wings for
flight. However, the evidence supporting Microraptor gui being a dinosaur is
overwhelming. Microraptor gui has a digit pattern of 1-2-3 digits rather than the 2-3-4
digits as seen in birds and the “killer” claw which is characteristic in most basal
dramaeosuars. The next logical question is where does Microraptor gui fit into the
debate over phylogenetic therapod/bird origin. Xing Xu proposes that Microraptor gui is
part of a tetrapteryx stage of evolution. In 1915 William Beebe proposed that the first
bird would be a four-winged glider. Evidence for Beebe’s hypothesis comes from the
asymmetrical feather vanes that indicate an aerodynamic morphology for flying. With all
this debate over Microraptor gui and the origin of birds, people like Allan Feduccia
question whether the fossil is a forgery like Archeoraptor was later determined. Further
study is needed on Microraptor gui and similar specimens to better understand the origin
of birds, beginning of flight and what our world was like 110 Ma ago.